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George Tai-Jen Chen
,
Chung-Chieh Wang
, and
An-Hsiang Wang

over southern China but temperatures there were only 18°–21°C ( Figs. 8f , 1c ), a clear indication for the existence of CAA at low levels. 4. Frontogenetical function and processes Using the method described in section 2b , the 2D frontogenetical function of Ninomiya (1984) was calculated. The interpretation of the pattern of F in relation to the frontal thermal gradient pattern follows the principle below: intensification (weakening) of the front or frontogenesis (frontolysis) occurs when

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David R. Novak
,
Brian A. Colle
, and
Ron McTaggart-Cowan

at 700 hPa beneath the upper PV elongation in the cyclone’s dry slot ( Fig. 20b ). Piecewise inversion of these anomalies confirmed that the diabatic PV anomaly in eastern New England was dominant in creating frontolysis (not shown). Frontolysis values induced by the diabatic PV anomaly at 2100 UTC 12 February were ∼25% of the total balanced frontogenesis. Thus, as with the 25 December 2002 case, a diabatic PV anomaly helped shift height falls east of the primary band, and weakened frontogenesis

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Carl M. Thomas
and
David M. Schultz

.e., frontolysis) were also created ( Fig. 12 ). The regions of frequent regions of frontolysis were similar to those for frontogenesis, although there were some minor quantitative differences (cf. Figs. 11 and 12 ). Fig . 12. Frequency of 850-hPa Petterssen frontolysis less than −0.15 K (100 km) −1 (3 h) −1 (%, colored according to scale) for (a) December, (b) March, (c) June, and (d) September. When is used in the frontogenesis function, the similarity between ) and ) is also apparent (cf. Figs

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Eigo Tochimoto
and
Hiroshi Niino

accompanied by northeast–southwest-tilted broadening troughs wrapping themselves up cyclonically and poleward. Shapiro et al. (1999) further added the term LC3 for the life cycle of the cyclone simulated in anticyclonic background shear. The location of cyclones relative to the region of strong environmental temperature gradient is also closely related to the warm and cold frontal structures. When a cyclone is located over a region of strong environmental horizontal temperature gradient, frontogenesis

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Jason C. Shafer
and
W. James Steenburgh

( Fig. 23c ). Further, diabatic frontolysis is occurring along the incipient cold front (not shown for clarity). This F D distribution explains why the total frontogenesis maximum is shifted into the prefrontal environment and occurs because the NARR-analyzed diabatic heating minimum is located along or just ahead of the developing front ( Fig. 23d ). As discussed below, this represents an unrealistic diabatic heating distribution. At −6 h, which represents a composite mean time of 1500 MST, total

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Naoko Kitabatake

resolved into natural coordinates ( s , n ) defined by the local orientation of θ e contours in the isobaric surface, such that where Thus the components of the vector frontogenesis in Eq. (3) are given as follows: Negative (positive) F n corresponds to the traditional frontogenesis (frontolysis) defined by Petterssen (1956) , while positive (negative) F s corresponds to the cyclonic (anticyclonic) rotational frontogenesis( Keyser et al. 1988 ; Martin 1999 ; Harr and Elsberry 2000 ). Note

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David M. Schultz
and
John A. Knox

), sea level pressure (black lines every 2 hPa), and 900-hPa frontogenesis [K (100 km) −1 (3 h) −1 , shaded according to scale, solid (dashed) lines surrounding shading represent frontogenesis (frontolysis) values of ±1.5 K (100 km) −1 (3 h) −1 ]. Rectangles identify regions where banded clouds and precipitation were observed from satellite and radar imagery. Fig . 5. Unfiltered, 0.5° elevation-angle, radar reflectivity factor (dB Z ) from the nationwide Weather Surveillance Radar-1988 Doppler

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Victoria A. Sinclair
,
Sami Niemelä
, and
Matti Leskinen

, there was little shear and strong stratification, which together lead to a shallower, less turbulent boundary layer than onshore. Horizontal gradients in surface sensible heat fluxes can result in either frontolysis or frontogenesis. Observations of atmospheric variables and measurements of sensible heat fluxes from two SMEARs ( Fig. 14 ), one located at Hyytiälä in central Finland (SMEAR II) and the second at Kumpula in Helsinki (SMEAR III), are analyzed and compared to the AROME forecast. The

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Forest Cannon
,
Jason M. Cordeira
,
Chad W. Hecht
,
Joel R. Norris
,
Allison Michaelis
,
Reuben Demirdjian
, and
F. Martin Ralph

February 2017 case study is also apparent in an evaluation of 192 GPM-DPR transects across ARs during October–April 2014–18. The 192 transects are partitioned into the 65 (one-third of the total) that contained the largest frontogenesis values in the AR transect and compared to the 65 with the weakest frontogenesis values (negative values indicate frontolysis). Note that the centroids of the individual AR transects in the high- and low-frontogenesis populations are scattered spatially so that the

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Andrew C. Winters
,
Daniel Keyser
, and
Lance F. Bosart

, https://doi.org/10.1175/1520-0469(1949)006<0330:CTOTHT>2.0.CO;2 . 10.1175/1520-0469(1949)006<0330:CTOTHT>2.0.CO;2 Newton , C. W. , 1954 : Frontogenesis and frontolysis as a three-dimensional process . J. Meteor. , 11 , 449 – 461 , https://doi.org/10.1175/1520-0469(1954)011<0449:FAFAAT>2.0.CO;2 . 10.1175/1520-0469(1954)011<0449:FAFAAT>2.0.CO;2 Nielsen-Gammon , J. W. , and R. J. Lefevre , 1996 : Piecewise tendency diagnosis of dynamical processes governing the development of an upper

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